Abstract:

There is provided an optical characteristic measuring method for measuring
an optical characteristic of an optical system which forms, on a second
plane, an image of an object arranged on a first plane, the optical
characteristic measuring method including: arranging, on the first plane,
a first area through which a measuring light passes or by which the
measuring light is reflected; arranging a second area, through which the
measuring light passes or by which the measuring light is reflected, on
the second plane at a position corresponding to the first area; and
detecting, via one of the first area and the second area, a light amount
of the measuring light via the optical system and the other of the first
area and the second area; wherein at least one of the first area and the
second area has a shape such that a light amount, of the measuring light
which passes or which is reflected via the optical system, is changed
depending on the optical characteristic.

Claims:

1. An optical characteristic measuring method for measuring an optical
characteristic of an optical system which forms, on a second plane, an
image of an object arranged on a first plane, the optical characteristic
measuring method comprising:arranging, on the first plane, a first area
through which a measuring light passes or by which the measuring light is
reflected;arranging a second area, through which the measuring light
passes or by which the measuring light is reflected, on the second plane
at a position corresponding to the first area; anddetecting, via one of
the first area and the second area, a light amount of the measuring light
via the optical system and the other of the first area and the second
area;wherein at least one of the first area and the second area has a
shape such that a light amount, of the measuring light which passes or
reflected via the optical system, is changed depending on the optical
characteristic.

2. The optical characteristic measuring method according to claim 1,
wherein the shape of the first area or the second area is changed in a
direction which intersects a measuring direction of the optical
characteristic.

3. The optical characteristic measuring method according to claim 1,
wherein the first area and the second area have mutually different
shapes.

4. The optical characteristic measuring method according to claim 1,
wherein the shape of the first area or the second area has an angle
θ of 0<θ<90 degrees with respect to a direction of the
measuring of the optical characteristic.

5. The optical characteristic measuring method claim 1, wherein the shape
of the first area or the second area has a curved line in a direction
which intersects a direction of the measuring of the optical
characteristic.

6. The optical characteristic measuring method according to claim 1,
wherein two or more pieces of the first area are arranged in the first
plane; andtwo or more pieces of the second area are arranged in the
second plane corresponding to the two or more pieces of the first area.

7. The optical characteristic measuring method according to claim 6,
wherein types of the two or more pieces of the first area are mutually
different.

8. The optical characteristic measuring method according to claim 6,
wherein types of the two or more pieces of the second area are mutually
different.

9. The optical characteristic measuring method according to claim 1,
wherein the optical characteristic is an aberration which is asymmetrical
with respect to an optical axis of the optical system in relation to a
measuring direction of the optical characteristic.

10. An optical characteristic adjusting method comprising:measuring an
optical characteristic of an optical system in accordance with the
optical characteristic measuring method as defined in claim 1;
andadjusting the optical characteristic of the optical system by using a
measurement result obtained in the measuring.

11. The optical characteristic adjusting method according to claim 10,
wherein in the adjusting, the optical characteristic is adjusted by
machining or exchanging at least one optical member which constructs the
optical system.

12. The optical characteristic adjusting method according to claim 10,
wherein the optical characteristic is adjusted in the adjusting by moving
at least one optical member which constructs the optical system in a
direction of an optical axis of the optical system, by shifting or
inclining the at least one optical member in a direction perpendicular to
the optical axis, or by rotating the at least one optical member about a
center of the optical axis.

13. An exposure apparatus which forms a pattern of a mask on a
photosensitive substrate, the exposure apparatus by comprising:an optical
system which is adjusted in accordance with the optical characteristic
adjusting method as defined in claim 10.

14. An exposure apparatus which forms a pattern of a mask via an optical
system on a photosensitive substrate, the exposure apparatus comprising:a
first pattern having a first area which is arranged on one of an object
plane and an image plane of the optical system and through which a
measuring light passes or by which the measuring light is reflected;a
second pattern having a second area which is arranged, on the other of
the object plane and the image plane of the optical system, at a position
corresponding to the first area and through which the measuring light
passes or by which the measuring light is reflected; anda detecting
section which detects, via one of the first pattern and the second
pattern, a light amount of measuring light via the optical system and the
other of the first pattern and the second pattern;wherein at least one of
the first area and the second area has a shape such that a light amount,
of the measuring light which passes or reflected via the optical system,
is changed depending on an optical characteristic of the optical system.

15. An exposure method for forming a pattern of a mask on a photosensitive
substrate, the exposure method comprising:illuminating the pattern;
andforming the illuminated pattern on the photosensitive substrate by an
optical system adjusted in accordance with the optical characteristic
adjusting method as defined in claim 10.

16. An exposure apparatus producing method for producing an exposure
apparatus which forms a pattern of a mask via an optical system on a
photosensitive substrate, the exposure apparatus producing method
comprising:adjusting an optical characteristic of the optical system in
accordance with the optical characteristic adjusting method as defined in
claim 10; andinstalling, in the exposure apparatus, the adjusted optical
system.

17. An exposure apparatus producing method for producing an exposure
apparatus which forms a pattern of a mask via an optical system on a
photosensitive substrate, the exposure apparatus producing method
comprising:installing the optical system in the exposure apparatus;
andadjusting an optical characteristic of the optical system installed in
the exposure apparatus in accordance with the optical characteristic
adjusting method as defined in claim 10.

Description:

CROSS-REFERENCES TO RELATED APPLICATIONS

[0001]This application is a Continuation Application of International
Application No. PCT/JP2008/061496 which was filed on Jun. 24, 2008
claiming the conventional priority of Japanese patent Application No.
2007-167857 filed on Jun. 26, 2007.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The present invention relates to an optical characteristic measuring
method for measuring an optical characteristic of an optical system
usable to produce an electronic device including, for example,
semiconductor elements and liquid crystal display elements in the
lithography step; an optical characteristic adjusting method for
adjusting the optical characteristic of the optical system; an exposure
apparatus provided with the optical system adjusted in accordance with
the adjusting method; an exposure method based on the use of the exposure
apparatus; and an exposure apparatus producing method for producing the
exposure apparatus.

[0004]2. Description of the Related Art

[0005]For example, when a semiconductor element or a liquid crystal
display element, etc. is produced, an exposure apparatus is used to
expose a substrate (a glass plate, a semiconductor wafer, etc.) coated
with a resist via an optical system (projection optical system) with a
pattern formed on a mask (for example, a reticle or a photomask). It is
necessary for the exposure apparatus to project the pattern formed on the
mask onto the substrate at a high resolution. Therefore, the optical
system, which is provided for the exposure apparatus, is designed to have
satisfactory optical characteristics in which various aberrations are
sufficiently corrected.

[0006]However, it is difficult to produce the optical system as exactly as
designed. The optical system, which is actually produced, has any optical
characteristic which is different from the designed optical
characteristic in some cases. Therefore, it is necessary that the optical
characteristic of the produced optical system should be measured to
adjust the optical characteristic of the optical system based on an
obtained measurement result. For example, Japanese Patent Application
Laid-open No. 2000-121498 describes a technique for measuring an optical
characteristic of an optical system, wherein an aperture, which is
provided on a substrate stage, is moved relative to a spatial image of a
measuring pattern formed via the optical system to obtain a light
intensity distribution of the spatial image of the measuring pattern
passing through the aperture so that the optical characteristic of the
imaging optical system is measured based on the amount of change of the
obtained intensity distribution of the spatial image.

SUMMARY OF THE INVENTION

[0007]In accordance with the progress of fine and minute mask patterns, it
becomes necessary that the optical characteristic of the optical system
provided on the exposure apparatus should be measured more highly
accurately. However, in the case of the conventional method for measuring
the optical characteristic, the intensity distribution of the spatial
image is obtained by moving the aperture provided on the substrate stage
relative to the spatial image of the measuring pattern as described
above. Therefore, the movement accuracy of the substrate stage greatly
affects the measurement accuracy of the optical characteristic.

[0008]On the other hand, it is conceived that the intensity distribution
of the spatial image of the measuring pattern is obtained by directly
detecting the spatial image of the measuring pattern via the optical
system by a sensor such as CCD or the like without moving the substrate
stage. However, in this case, it is necessary that the sensor should have
a spatial resolution required to detect the intensity distribution of the
spatial image. That is, it is necessary that the pixels of the sensor
such as CCD or the like should be sufficiently small-sized depending on
the spatial resolution. However, at present, any sensor, which satisfies
this requirement, does not exist. Therefore, it has been difficult to
measure the optical characteristic of the optical system highly
accurately.

[0009]Another method is also known, in which a magnifying optical system
is arranged on the side of the light-incident surface of the sensor in
order to obtain a necessary spatial resolution by the sensor such as CCD
or the like. However, a problem arises such that the measuring system is
large-sized due to the arrangement of the magnifying optical system.

[0010]An object of the present invention is to provide an optical
characteristic measuring method which makes it possible to measure an
optical characteristic of an optical system highly accurately, an optical
characteristic adjusting method which makes it possible to adjust the
optical characteristic of the optical system highly accurately, an
exposure apparatus which is provided with the optical system adjusted in
accordance with the adjusting method, an exposure method which uses the
exposure apparatus, and an exposure apparatus producing method for
producing the exposure apparatus.

[0011]There is provided an optical characteristic measuring method for
measuring an optical characteristic of an optical system which forms, on
a second plane, an image of an object arranged on a first plane, the
optical characteristic measuring method comprising: arranging, on the
first plane, a first area through which a measuring light passes or by
which the measuring light is reflected; arranging a second area, through
which the measuring light passes or by which the measuring light is
reflected, on the second plane at a position corresponding to the first
area; and detecting, via one of the first area and the second area, a
light amount of the measuring light via the optical system and the other
of the first area and the second area; wherein at least one of the first
area and the second area has a shape such that the light amount, of the
measuring light which passes or reflected via the optical system, is
changed depending on the optical characteristic.

[0012]There is provided an optical characteristic adjusting method
comprising: measuring an optical characteristic of an optical system in
accordance with the optical characteristic measuring method; and
adjusting the optical characteristic of the optical system by using a
measurement result obtained in the measuring.

[0013]There is provided an exposure apparatus which forms a pattern of a
mask on a photosensitive substrate, the exposure apparatus comprising an
optical system which is adjusted in accordance with the optical
characteristic adjusting method.

[0014]There is provided an exposure apparatus which forms a pattern of a
mask via an optical system on a photosensitive substrate, the exposure
apparatus comprising: a first pattern having a first area which is
arranged on one of an object plane and an image plane of the optical
system and through which a measuring light passes or by which the
measuring light is reflected; a second pattern having a second area which
is arranged, on the other of the object plane and the image plane of the
optical system, at a position corresponding to the first area and through
which the measuring light passes or by which the measuring light is
reflected; and a detecting section which detects, via one of the first
pattern and the second pattern, a light amount of the measuring light via
the optical system and the other of the first pattern and the second
pattern; wherein at least one of the first area and the second area has a
shape such that the light amount, of the measuring light which passes or
which is reflected via the optical system, is changed depending on the
optical characteristic.

[0015]There is provided an exposure method for forming a pattern of a mask
on a photosensitive substrate, the exposure method comprising:
illuminating the pattern; and forming the illuminated pattern on the
photosensitive substrate by an optical system adjusted in accordance with
the optical characteristic adjusting method.

[0016]There is provided an exposure apparatus producing method for
producing an exposure apparatus which forms a pattern of a mask via an
optical system on a photosensitive substrate, the exposure apparatus
producing method comprising: adjusting an optical characteristic of the
optical system in accordance with the optical characteristic adjusting
method; and installing, in the exposure apparatus, the adjusted optical
system.

[0017]There is provided an exposure apparatus producing method for
producing an exposure apparatus which forms a pattern of a mask via an
optical system on a photosensitive substrate, the exposure apparatus
producing method comprising: installing the optical system in the
exposure apparatus; and adjusting an optical characteristic of the
optical system installed in the exposure apparatus in accordance with the
optical characteristic adjusting method.

[0018]According to the optical characteristic measuring method, at least
one of the first area and the second area has a shape such that the light
amount of the measuring light which passes or which is reflected via the
optical system is changed depending on the optical characteristic of the
optical system. Therefore, the optical characteristic of the optical
system can be measured highly accurately without scanning the spatial
image of one of the first area and the second area relative to the other
of the first area and the second area.

[0019]According to the optical characteristic adjusting method, the
optical characteristic of the optical system is measured in accordance
with the optical characteristic measuring method, and the optical
characteristic of the optical system is adjusted by using the obtained
measurement result. Therefore, it is possible to obtain the optical
system having a satisfactory optical characteristic.

[0020]According to the exposure apparatus, the exposure apparatus is
provided with the optical system adjusted in accordance with the optical
characteristic adjusting method. Therefore, the pattern of the mask can
be formed on the photosensitive substrate at a high resolution via the
optical system having the satisfactory optical characteristic in relation
to the image of the pattern arranged on the first plane.

[0021]According to the exposure apparatus, at least one of the first area
and the second area has a shape such that the light amount, of the
measuring light allowed to pass or reflected via the optical system, is
changed depending on the optical characteristic of the optical system.
Therefore, the optical characteristic of the optical system can be
measured highly accurately without scanning the spatial image of one of
the first area and the second area relative to the other of the first
area and the second area. Therefore, the image of the pattern of the mask
can be formed on the photosensitive substrate at a high resolution via
the optical system having the satisfactory optical characteristic.

[0022]According to the exposure method, the pattern of the mask can be
formed on the photosensitive substrate at a high resolution by the
optical system adjusted in accordance with the optical characteristic
adjusting method.

[0023]According to the exposure apparatus producing method, the optical
characteristic of the optical system is adjusted in accordance with the
optical characteristic adjusting method, and the adjusted optical system
is installed in (provided on, disposed in) the exposure apparatus.
Alternatively, the optical system is installed in or provided on the
exposure apparatus, and the optical characteristic of the optical system
installed in the exposure apparatus is adjusted in accordance with the
optical characteristic adjusting method. Therefore, it is possible to
produce the exposure apparatus provided with the optical system having
the satisfactory optical characteristic.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 shows a schematic construction of a projection exposure
apparatus according to an embodiment.

[0025]FIG. 2 shows a flow chart for illustrating a method for producing
the projection exposure apparatus according to the embodiment.

[0026]FIG. 3 shows a flow chart for illustrating a method for measuring
the optical characteristic of the projection optical system according to
the embodiment.

[0027]FIG. 4 shows a construction of a measuring mask according to the
embodiment.

[0028]FIGS. 5A and 5B show a construction of a measuring device according
to the embodiment.

[0029]FIG. 6 illustrates a relationship of the total amounts or sum totals
of two light amounts when there is no distortion of the projection
optical system.

[0030]FIG. 7 illustrates a relationship of the total amounts or sum totals
of two light amounts when there is a distortion of the projection optical
system.

[0031]FIG. 8 illustrates a relationship of the total amounts or sum totals
of two light amounts when there is a distortion of the projection optical
system.

[0032]FIG. 9 shows a graph illustrating a relationship between the
distortion of the projection optical system and the difference between
the total amounts of the two light amounts.

[0033]FIG. 10 shows a construction of another measuring mask according to
the embodiment.

[0034]FIG. 11 shows a construction of another measuring device according
to the embodiment.

[0035]FIG. 12 shows a construction of still another measuring mask
according to the embodiment.

[0036]FIG. 13 shows a construction of still another measuring device
according to the embodiment.

[0037]FIG. 14 shows a construction of still another measuring mask
according to the embodiment.

[0038]FIG. 15 shows a construction of still another measuring device
according to the embodiment.

[0039]FIG. 16 shows a construction of another apertures according to the
embodiment.

[0040]FIG. 17 shows constructions of still another apertures according to
the embodiment.

[0041]FIG. 18 shows a flow chart illustrating a method for producing a
semiconductor device as a microdevice according to the embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042]A projection exposure apparatus (exposure apparatus) according to an
embodiment will be explained below with reference to the drawings. FIG. 1
shows a schematic construction of the projection exposure apparatus
according to this embodiment.

[0043]In the following description, an XYZ rectangular coordinate system
is set as shown in each of the drawings. An explanation will be made
about the positional relationship of respective members with reference to
the XYZ rectangular coordinate system. The XYZ rectangular coordinate
system is set so that the X axis and the Y axis are parallel to a wafer
(photosensitive substrate) W, and the Z axis is set in a direction
perpendicular to the wafer W. It is assumed that the X axis extends in a
direction parallel to the sheet surface of FIG. 1, and the Y axis extends
in a direction perpendicular to the sheet surface of FIG. 1.

[0044]The projection exposure apparatus shown in FIG. 1 includes a light
source (not shown) which supplies an exposure light (exposure light
beam); an illumination optical system (not shown) which uniformly
illuminates a mask M with the light or light beam from the light source;
and a projection optical system (optical system) 15 which images a
pattern formed on the mask M on the wafer W. The projection exposure
apparatus further includes a mask stage 12 which holds the mask M and
which is capable of adjusting the position of a pattern formation surface
of the mask M with respect to the object plane of the projection optical
system 15 (plane parallel to the XY plane); and a wafer stage 16 which
holds the wafer W and which is capable of adjusting the position of the
surface of the wafer W with respect to the image plane of the projection
optical system 15 (plane parallel to the XY plane).

[0045]The embodiment of the present invention is explained as exemplified
by the wafer W as the substrate by way of example. However, the substrate
is not limited to the wafer W, and may be a glass plate.

[0046]The light or light beam, which exits from the light source,
illuminates the mask M via the illumination optical system at a uniform
illuminance in a superimposed or overlay manner. Those usable as the
light source include light sources of the mercury lamp, the KrF excimer
laser, the ArF excimer laser, the F2 laser, the extreme ultraviolet
light, etc.

[0047]The light, via or passing through the mask M, comes into the
projection optical system 15. The projection optical system 15 is
constructed of a plurality of optical members. The projection optical
system 15 images the pattern formed on the mask M at a predetermined
magnification (reducing magnification, 1× magnification, or
magnifying magnification) on the wafer W. The wafer stage 16 which holds
the wafer W is constructed of an XY stage which is movable in the
directions of the X axis and the Y axis, a Z stage which is movable in
the direction of the Z axis and which is inclinable with respect to the Z
axis, etc. The Z stage of the wafer stage 16 is provided with a wafer
holder 17 which attracts and holds the wafer W. Respective exposure
areas, which are formed on the wafer W, are successively exposed with the
transfer pattern of the mask M while the wafer stage 16 is
two-dimensionally driven and controlled in the XY plane. The projection
exposure apparatus is provided with a wafer stage interferometer 18 which
measures a position in the XY plane on the wafer W, and an autofocus
system 19 which measures the position of the wafer W in the Z direction.
Measurement results obtained by the wafer stage interferometer 18 and the
autofocus system 19 are outputted to a controller 30.

[0048]The projection exposure apparatus is provided with a measuring
device 20 which measures the optical characteristic of the projection
optical system 15. As shown in FIG. 5 (FIGS. 5A and 5B), the measuring
device 20 includes a pattern plate 20c which has two apertures or
openings (light-receiving patterns) 43, 44; and a sensor section 20a (CCD
or a light amount detection sensor, etc.) which serves as a detecting
section which receives the lights passing through the two apertures 43,
44. With reference to FIG. 1, the measuring device 20 is installed or
provided on the wafer stage 16 and in the vicinity of the wafer holder
17. The pattern formation surface of the pattern plate 20c is set at a
height approximately same as that of the surface of the wafer W. The
construction of the measuring device 20 will be described later on. A
measurement result obtained by the measuring device 20 is outputted to
the controller 30.

[0049]The controller 30 adjusts the optical characteristic of the
projection optical system 15 based on the measurement result outputted
from the measuring device 20. A measuring method and an adjusting method
for the optical characteristic of the projection optical system 15 will
be described and explained in detail later on.

[0050]Next, an explanation will be made about a method for producing the
projection exposure apparatus (exposure apparatus) according to this
embodiment with reference to a flow chart shown in FIG. 2.

[0051]At first, the projection optical system 15 is designed so that
various aberrations are sufficiently corrected to provide satisfactory
optical characteristics. The projection optical system 15, which is
produced after the design, is installed or arranged in the projection
exposure apparatus at a predetermined position (Step S10, installing
step). Subsequently, the optical characteristic, of the projection
optical system 15 installed in the projection exposure apparatus in Step
S10, is measured (Step S11, measuring step). That is, various
aberrations, which result from a variety of factors, remain in some cases
in the actually produced projection optical system. Therefore, the
optical characteristic of the projection optical system is measured. It
is judged whether or not the optical characteristic of the projection
optical system 15 is satisfactory based on the measurement result (Step
S12). If the optical characteristic of the projection optical system 15
is not satisfactory, the optical characteristic of the projection optical
system 15 is adjusted (Step S13, adjusting step). The routine returns to
Step S11 to measure the optical characteristic of the projection optical
system 15 again. On the other hand, if the optical characteristic of the
projection optical system 15 is satisfactory, the production of the
projection exposure apparatus is completed.

[0052]FIG. 3 shows a flow chart for illustrating the method for measuring
the optical characteristic of the projection optical system 15 according
to this embodiment (measuring step in Step S11).

[0053]Here, the optical characteristic of the projection optical system 15
according to this embodiment includes the aberration (aberration
represented by the comatic aberration and the distortion) which is
asymmetrical with respect to the optical axis of the projection optical
system 15 in relation to the measuring direction of the optical
characteristic. In this embodiment, an explanation will be made as
exemplified by the measurement of the distortion of the projection
optical system 15 by way of example.

[0054]At first, a measuring mask, having measuring patterns 40, 41 which
are formed in the measuring mask and through which the measuring light is
passable, is arranged on the mask stage 12 (Step S20). FIG. 4 shows the
construction of the measuring mask M1. As shown in FIG. 4, the measuring
mask M1 has the two measuring patterns 40, 41 which are formed in the
measuring mask M1 and each of which has a width of several μm in the
measuring direction (X direction). It is desirable that the widths of the
measuring patterns 40, 41 are thick to such an extent that no influence
is exerted by the comatic aberration, etc.

[0055]Subsequently, by moving the wafer stage 16 in the XY directions, two
apertures 43, 44 which are formed on the pattern plate 20c of the
measuring device 20 are arranged in the projection area (field) of the
projection optical system 15 (Step S21). The two apertures 43, 44 have
shapes different from those of the measuring patterns 40, 41 formed on
the measuring mask M1; and the shapes of the two apertures 43, 44 are
changed in the direction (Y direction) perpendicular to the measuring
direction for the optical characteristic of the projection optical system
15. That is, each of the apertures 43, 44 has a shape such that the light
amount, of the measuring light passing via the projection optical system
15, is changed depending on the distortion of the projection optical
system 15.

[0056]Specifically, as shown in FIG. 5A, the shapes of the apertures 43,
44 are triangular shapes which are arranged so that their bases are
opposite to or facing each other respectively; and the oblique sides have
an angle θ of 0<θ<90 (degrees) with respect to the
measuring direction (X direction). The size of the angle θ is
determined depending on the magnitudes or dimensions of the required
measurement accuracy, the measurement range, and the dynamic range D. In
a case that it is intended to measure the distortion more highly
accurately, it is desirable that the size of the angle θ is nearer
to 90 degrees (however, the angle θ=90 degrees is excluded). When
the size of the dynamic range D is fixed, sizes H of the apertures 43,
44, which are provided in the direction (Y direction) perpendicular to
the measuring direction, are increased, as the size of the angle θ
approaches 90 degrees. The size H in the Y direction is determined
depending on, for example, the required measurement range.

[0057]The sensor section 20a, which is provided on the measuring device
20, is connected to a setting section which sets a light-receiving area
corresponding to the aperture 43, a light-receiving area corresponding to
the aperture 44, and a light-receiving area corresponding to a reference
aperture 45 in order to independently receive the measuring light passing
through the aperture 43, the measuring light passing through the aperture
44, and the measuring light passing through the reference aperture 45,
respectively, as described later on. The operation of the setting section
20b is controlled by the controller 30.

[0058]When the optical characteristic is measured, the measurement
accuracy is affected in some cases by the change in the light amount
(light amount change) of the measuring light illuminating the measuring
mask M1 therewith. Accordingly, in this embodiment, the pattern plate 20c
is formed with the reference aperture 45 in order to monitor the light
amount change of the measuring light. In a case that the light amount
change of the measuring light is monitored, the setting section 20b sets
the light-receiving area corresponding to the reference aperture 45 to
detect the measuring light passing through the reference aperture 45. The
light amount of the measuring light passing through the reference
aperture 45 is monitored, and the measurement result of the optical
characteristic of the projection optical system 15 is corrected based on
the monitoring result. Accordingly, it is possible to maintain the high
measurement accuracy.

[0059]Subsequently, the measuring mask M1, which is arranged in Step S20,
is illuminated with the light having a predetermined wavelength, i.e.,
the measuring light having the same wavelength as that of the light used
for the exposure (Step S22). The images of the measuring patterns are
projected onto the apertures 43, 44 of the measuring device 20, via the
measuring patterns 40, 41 and the projection optical system 15.

[0060]Subsequently, the sensor section 20a detects the measuring light
passing through the measuring pattern 40 and via the aperture 43 and the
measuring light passing through the measuring pattern 41 and via the
aperture 44 respectively in accordance with the setting operation
effected by the setting section 20b (Step S23). Specifically, the sensor
section 20a detects a total amount or sum total I1 of the light amount of
the measuring light passing through the aperture 43, and the sensor
section 20a detects a total amount or sum total I2 of the light amount of
the measuring light passing through the aperture 44. The total amounts
I1, I2 of the light amounts measured by the sensor section 20a are
outputted to the controller 30.

[0061]Subsequently, the total amounts I1, I2 of the light amounts, which
are detected in Step S23, are compared with each other (Step S24), and
the distortion of the projection optical system 15 is measured by using a
result of the comparison performed in Step S24 (Step S25, measuring
step). In this procedure, the positional relationship of the images of
the measuring patterns 40, 41 with respect to the apertures 43, 44 is set
so that the total amount I1 of the light amount of the measuring light
passing through the aperture 43 is identical with the total amount 12 of
the light amount of the measuring light passing through the aperture 44
as shown in FIG. 6 if the projection optical system 15 has no distortion
(in the case of the distortion amount=0). Therefore, if the projection
optical system 15 has no distortion (in the case of the distortion
amount=0), then the total amount I1 of the light amount of the measuring
light passing through the aperture 43 is equal to the total amount 12 of
the light amount of the measuring light passing through the aperture 44,
and the difference between the light amounts ΔI is
ΔI=I1-I2=0.

[0062]On the other hand, if the projection optical system 15 has any
distortion (in the case of the distortion amount≠0), the positions
of the images of the measuring patterns 40, 41 with respect to the
apertures 43, 44 are changed as shown in FIG. 7 or 8. Therefore, the
total amount I1 of the light amount of the measuring light passing
through the aperture 43 is different from the total amount I2 of the
light amount of the measuring light passing through the aperture 44, and
the difference between the light amounts ΔI is
ΔI=I1-I2≠0. As shown in FIG. 9, the distortion and ΔI
are in a relationship of direct proportion. Therefore, the distortion of
the projection optical system 15 can be measured by determining ΔI.

[0063]The adjustment of the optical characteristic of the projection
optical system 15 (adjusting step in Step S13), which is based on the
amount of the distortion of the projection optical system 15 measured in
Step S11 in the flow chart shown in FIG. 2, is executed by calculating
the adjustment amount to correct the distortion so that the distortion of
the projection optical system 15 is adjusted. Specifically, the
distortion of the projection optical system 15 is adjusted by subjecting
at least one of the optical members constructing the projection optical
system 15 to the movement in the optical axis direction of the projection
optical system 15, the shift or the inclination in the direction
perpendicular to the optical axis of the projection optical system 15,
and/or the rotation about the center of the optical axis of the
projection optical system 15.

[0064]According to the projection exposure apparatus concerning this
embodiment, the apertures 43, 44 of the light-receiving pattern have such
shapes that the light amount of the measuring light passing via the
projection optical system 15 are changed depending on the distortion
amount of the projection optical system 15. Therefore, it is possible to
highly accurately measure the distortion of the projection optical system
15 without moving the aperture provided on the wafer stage relative to
the spatial image of the measuring pattern as performed in the
conventional method for measuring the optical characteristic. Therefore,
the projection optical system 15, which has the satisfactory optical
characteristic, can be obtained by adjusting the distortion of the
projection optical system 15 by using the measurement result. The image
of the pattern of the mask M can be formed at a high resolution on the
wafer W via the projection optical system 15 having the satisfactory
optical characteristic.

[0065]According to the method for measuring the optical characteristic
concerning this embodiment, it is unnecessary to move the aperture
provided on the wafer stage relative to the spatial image of the
measuring pattern, unlike the conventional method for measuring the
optical characteristic. Therefore, it is possible to highly accurately
measure the optical characteristic (distortion) of the projection optical
system 15 without being affected by the movement accuracy of the wafer
stage. The movement time for the wafer stage is also unnecessary.
Therefore, it is possible to greatly shorten the measuring time.
According to the method for measuring the optical characteristic
concerning this embodiment, it is enough to detect the total amounts of
the light amounts of the measuring light passing through the apertures
43, 44. Therefore, it is possible to use a sensor having a rough spatial
resolution without depending on the spatial resolution of the pattern.
Further, it is enough that the light amount of the measuring light is
directly detected by the sensor section. Therefore, it is unnecessary to
provide any relay optical system, etc. between the light-receiving
pattern and the sensor section. It is possible to measure the optical
characteristic of the projection optical system 15 by the compact and low
cost measuring device.

[0066]According to the method for adjusting the optical characteristic
concerning this embodiment, the optical characteristic of the projection
optical system 15 is measured in accordance with the method for measuring
the optical characteristic concerning this embodiment, and the optical
characteristic of the projection optical system 15 is adjusted by using
the obtained measurement result. Therefore, it is possible to obtain the
optical system having the satisfactory optical characteristic in which
the aberration is sufficiently corrected.

[0067]According to the method for producing the projection exposure
apparatus concerning this embodiment, the optical characteristic of the
projection optical system 15 is measured and adjusted in accordance with
the method for measuring the optical characteristic and the method for
adjusting the optical characteristic concerning this embodiment.
Therefore, it is possible to produce the exposure apparatus provided with
the projection optical system having the satisfactory optical
characteristic in which the aberration is sufficiently corrected.

[0068]In the method for measuring the optical characteristic according to
this embodiment, the distortion of the projection optical system 15 is
measured by using the measuring mask M1 as shown in FIG. 4 and the
measuring device 20 as shown in FIG. 5 (FIGS. 5A and 5B). However, the
distortion of the projection optical system 15 may be measured, for one
measuring point, by using a measuring mask having two or more sets of
measuring patterns having identical shapes and a measuring device having
two or more sets of apertures. The distortion of the projection optical
system 15 may be measured by using, for example, a measuring mask M2
which is formed with three sets of measuring patterns 40a, 41a, 40b, 41b,
40c, 41c as shown in FIG. 10 and a measuring device 20A which is provided
with a pattern plate formed with three sets of apertures 43a, 44a, 43b,
44b, 43c, 44c as shown in FIG. 11. The shapes of the apertures 43a to 43c
are same as or equivalent to the shape of the aperture 43 shown in FIG.
5, and the shapes of the measuring patterns 44a to 44c are same as or
equivalent to the shape of the aperture 44 shown in FIG. 5.

[0069]In this case, a total amount 13 or an average value A3 of the light
amounts of the measuring light passing through the aperture 43a via the
measuring pattern 40a and the projection optical system 15, the measuring
light passing through the aperture 43b via the measuring pattern 40b and
the projection optical system 15, and the measuring light passing through
the aperture 43c via the measuring pattern 40c and the projection optical
system 15 is measured. Similarly, a total amount 14 or an average value
A4 of the light amounts of the measuring light passing through the
aperture 44a via the measuring pattern 41a and the projection optical
system 15, the measuring light passing through the aperture 44b via the
measuring pattern 41b and the projection optical system 15, and the
measuring light passing through the aperture 44c via the measuring
pattern 41c and the projection optical system 15 is measured. The
distortion of the projection optical system 15 is measured based on the
result of comparison between the total amount 13 or the average value A3
of the light amounts and the total amount 14 or the average value A4 of
the light amounts. According to this measuring method, it is possible to
measure the distortion amount more highly accurately.

[0070]Alternatively, the distortion of the projection optical system 15
may be measured by using, for example, a measuring mask M3 which is
formed with three sets of measuring patterns 40d, 40e, 40f, 41d, 41e, 41f
as shown in FIG. 12 and a sensor 20B which is provided with a pattern
plate formed with three sets of apertures 43d, 43e, 43f, 44d, 44e, 44f as
shown in FIG. 13. The respective shapes of the apertures 43d to 43f, 44d
to 44f are same as or equivalent to the shape of the aperture 43 or the
aperture 44 shown in FIG. 5.

[0071]In this case, a total amount 15 of the light amounts of the
measuring light passing through the aperture 43d via the measuring
pattern 40d and the projection optical system 15, the measuring light
passing through the aperture 43e via the measuring pattern 40e and the
projection optical system 15, and the measuring light passing through the
aperture 43f via the measuring pattern 40f and the projection optical
system 15 is measured. Similarly, a total amount 16 of the light amounts
of the measuring light passing through the aperture 44d via the measuring
pattern 41d and the projection optical system 15, the measuring light
passing through the aperture 44e via the measuring pattern 41e and the
projection optical system 15, and the measuring light passing through the
aperture 44f via the measuring pattern 41f and the projection optical
system 15 is measured. The distortion of the projection optical system 15
is measured based on the result of comparison between the total amount 15
of the light amounts and the total amount 16 of the light amounts.
According to this measuring method, it is also possible to perform the
measurement more highly accurately.

[0072]In the method for measuring the optical characteristic according to
this embodiment, the light amount of the measuring light is detected at
one image point in the projection area of the projection optical system
15. However, the light amount of the measuring light may be measured at a
plurality of image points in the projection area of the projection
optical system 15. The optical characteristic of the projection optical
system 15 may be measured by using, for example, a measuring mask M4
which is formed with five sets of measuring patterns 50 to 54 as shown in
FIG. 14 and a measuring device 20C which is provided with a pattern plate
formed with five sets of light-receiving patterns 55 to 59 as shown in
FIG. 15.

[0073]As shown in FIG. 14, two types of measuring patterns, which are of
mutually different types, are formed on the measuring mask M4. In this
embodiment, each of the measuring patterns 50 to 54 is formed as the two
types of measuring patterns of the mutually different types. Each of the
measuring patterns is formed with two line patterns each of which has a
width of several μm and which are formed in the two measuring
directions (X direction and Y direction) perpendicular to each other. As
shown in FIG. 15, two types of apertures, which are of mutually different
types, are formed on the pattern plate of the measuring device 20. In
this embodiment, the apertures, which have the same or equivalent shapes
as those of the apertures according to the embodiment described above,
are formed as the two types of the apertures of the mutually different
types corresponding to the measuring patterns 50 to 54, respectively. The
respective apertures are formed in the two measuring directions
perpendicular to each other.

[0074]In a case that the optical characteristic of the projection optical
system 15 is measured by using the measuring mask M4 and the measuring
device 20C, the light amount of the measuring light can be simultaneously
measured at a plurality of image heights in the projection area of the
projection optical system 15. Therefore, it is possible to measure the
optical characteristic of the projection optical system 15 at the
different image heights quickly and highly accurately. In this
embodiment, the measurement of the distortion has been explained by way
of example. However, in a case that the comatic aberration of the
projection optical system 15 is measured, it is appropriate to use a
measuring mask which is formed with a plurality of measuring patterns
having different widths and a measuring device which is provided with a
pattern plate formed with apertures according to this embodiment and
provided corresponding to the measuring patterns respectively. In the
case that the comatic aberration is measured, it is also allowable to use
only at least one of the aperture 43 and the aperture 44.

[0075]Even when the shape of the measuring pattern is identical or same,
it is also possible to perform the measurement in which the dynamic range
and/or the sensitivity is/are different, by providing two or more
apertures of mutually different types (for example, the forming
direction, the pitch, and the line width).

[0076]The setting section is connected to the measuring device 20B shown
in FIG. 11, the measuring device 20C shown in FIG. 13, and the measuring
device 20D shown in FIG. 15, in the same manner as the measuring device
20 shown in FIG. 5. One or more reference aperture or reference apertures
may be provided on the light-receiving pattern surface of each of the
measuring devices 20B to 20D to monitor the light amount of the measuring
light illuminating the measuring mask therewith.

[0077]In the method for measuring the optical characteristic according to
this embodiment, the distortion of the projection optical system 15 is
measured by comparing the total amount I1 of the light amounts of the
measuring light passing through the aperture 43 and the total amount 12
of the light amounts of the measuring light passing through the aperture
44. However, only the measuring light, which has passed through the
aperture 43 or the aperture 44, may be detected, and the distortion of
the projection optical system 15 can be measured in accordance with an
obtained detection result as well. For example, the measuring light,
which has passed through the aperture 43 (or the aperture 44), is
detected at every predetermined period of time, and the time-dependent
change of the amount of the distortion of the projection optical system
15 is measured in accordance with the time-dependent change amount of the
total amount I1 (or I2) of the light amounts of the measuring light
passing through the aperture 43 (or the aperture 44).

[0078]In this embodiment, the aperture shown in FIG. 5, 11, 13, or 15 has
the shape in which the change occurs depending on the optical
characteristic of the projection optical system 15. However, the shape of
the aperture shown in FIG. 5, 11, 13, or 15 may be formed on a measuring
mask, and the shape of the measuring pattern shown in FIG. 4, 10, 12, or
14 may be formed on a pattern plate of the measuring device. In a case
that the apertures, each of which has such a shape that the change occurs
depending on the optical characteristic of the projection optical system
15, are formed on a measuring mask and a pattern plate of the measuring
device, the shape of the measuring pattern formed on the measuring mask
and the shape of the aperture formed on the pattern plate may be mutually
different.

[0079]This embodiment is explained as exemplified by the apertures shown
in FIGS. 5, 11, 13, and 15 by way of example. However, for example, it is
also allowable to adopt apertures each of which has a curved line in the
direction (Y direction) perpendicular to the measuring direction, as
shown in FIG. 16. Alternatively, it is also allowable to adopt apertures
as shown in FIGS. 17A to 17F. That is, it is appropriate to adopt any
aperture having a shape which has an angle θ of 0<θ<90
(degrees) with respect to the measuring direction (X direction) so that
the light amount of the measuring light passing therethrough is changed
depending on the optical characteristic of the projection optical system
15.

[0080]In this embodiment, the optical characteristic of the projection
optical system is measured by using the aperture type measuring pattern
through which the light is passing as formed in a part of the light
shielding area and the aperture through which the light is passing as
formed in a part of the light shielding area. However, the measuring
pattern may be of the transmission type through which the light is
transmitted or of the reflection type by which the light is reflected,
and the aperture may be of the transmission type or of the reflection
type. This embodiment is illustrative of the exemplary case in which the
measuring light is detected by using the measuring pattern and the
aperture by way of example. However, the light-shielding area and the
area for allowing the light to pass therethrough may be inverted or
reversed. Alternatively, a liquid crystal display device may be used as
the measuring mask and/or the pattern plate to electrically generate the
measuring pattern and/or the aperture. Of course, a shutter mechanism may
be provided for the measuring mask and/or the pattern plate to
mechanically prepare or form the measuring pattern and/or the aperture.

[0081]In the embodiment described above, the light-receiving areas, which
distinctly receive the lights passing through the respective apertures
respectively, are set by the setting section in the light-receiving areas
of one sensor section. However, a plurality of sensor sections may be
used to receive the respective lights passing through the respective
apertures by the respective sensor sections.

[0082]In this embodiment, the optical characteristic of the projection
optical system 15 is measured by irradiating or radiating the measuring
light from the object side of the projection optical system 15 and by
detecting the measuring light via the image plane of the projection
optical system 15. However, the measuring light may be radiated from the
image plane side of the projection optical system 15, and the measuring
light may be detected via the object plane of the projection optical
system 15.

[0083]In this embodiment, the light amount of the measuring light passing
through the reference aperture is monitored so that no influence is
exerted by the change of the light amount of the illumination light.
However, the reference aperture may be omitted by determining the
difference ΔI in the light amount by using the expression of
ΔI=(I1-I2)/(I1+I2).

[0084]In the method for producing the projection exposure apparatus
according to this embodiment, the exemplary case has been explained by
way of example, in which the projection exposure apparatus is provided
with the measuring device which measures the optical characteristic of
the projection optical system 15, and the optical characteristic of the
projection optical system 15 is measured and adjusted after installing
the projection optical system 15 in the projection exposure apparatus.
However, the optical characteristic of the projection optical system 15
may be measured in accordance with the method for measuring the optical
characteristic according to this embodiment, and the optical
characteristic may be adjusted based on an obtained result before
installing the projection optical system 15 in the projection exposure
apparatus. As for the adjustment of the optical characteristic of the
projection optical system 15, in a case that the focus position is
corrected, then wedge-shaped pair glass members may be relatively
rotated, and/or the position of the stage may be controlled.

[0085]In this case, the optical characteristic of the projection optical
system 15 can be also adjusted by machining or processing (for example,
repolishing) or exchanging at least one of the optical members
constructing the projection optical system 15, in addition to the
adjustment of the optical characteristic of the projection optical system
15 as described above.

[0086]In this embodiment, the method for measuring the optical
characteristic of the projection optical system has been explained.
However, the optical characteristics of all imaging optical systems can
be measured by using the optical characteristic measuring method.

[0087]In this embodiment, the construction has been explained, in which
the measuring device 20 is attached to the wafer stage 16. However, the
measuring device 20 may be provided detachably with respect to the wafer
stage 16.

[0088]Both of the wafer stage and the measuring stage may be prepared for
the exposure apparatus, and the measuring device 20 may be provided on or
for the measuring stage.

[0089]The embodiment of the present invention is also applicable to a
liquid immersion type exposure apparatus in which the liquid is allowed
to intervene or is disposed between the projection optical system and the
wafer. The embodiment of the present invention is also applicable to an
EUV exposure apparatus which includes an illumination optical system and
a projection optical system constructed of reflection type optical
members, etc., wherein the extreme ultraviolet light (EUV light) is used
as the exposure light.

[0090]With the projection exposure apparatus according to the embodiment
described above, a microdevice (a semiconductor element, an image pickup
element, a liquid crystal display element, a thin film magnetic head,
etc.) can be produced by forming, on a photosensitive substrate (wafer
W), a transfer pattern formed by a mask M by using the projection optical
system 15 (forming step). An explanation will be made below with
reference to a flow chart shown in FIG. 18 about an exemplary procedure
adopted upon obtaining the semiconductor device as the microdevice by
forming a predetermined circuit pattern, for example, on the wafer W as
the photosensitive substrate by using the projection exposure apparatus
according to the embodiment described above.

[0091]At first, in Step S301 shown in FIG. 18, a metal film is
vapor-deposited on each of wafers W of 1 lot. Subsequently, in Step S302,
a photoresist is coated on a surface of the metal film on each of the
wafers W of 1 lot. After that, in Step S303, the pattern, which is formed
on the mask M, is illuminated with the illumination light by using the
projection exposure apparatus according to the embodiment described above
(illuminating step). The image of the pattern illuminated with the
illumination light is successively transferred to the respective shot
areas on each of the wafers W of 1 lot to perform the exposure via the
projection optical system 15 having the optical characteristic measured
and adjusted in accordance with the optical characteristic measuring
method and the optical characteristic adjusting method according to this
embodiment (exposure step). After that, the photoresist on each of the
wafers W of 1 lot is developed in Step S304, and then the etching is
performed by using the resist pattern as a mask on each of the wafers W
of 1 lot in Step S305. Accordingly, the circuit pattern, which
corresponds to the pattern of the mask M, is formed on each of the shot
areas on each of the wafers W.

[0092]After that, for example, circuit patterns of upper layers are
formed, and thus the device such as the semiconductor element or the like
is produced. According to the exposure method concerning this embodiment,
the exposure is performed by using the projection optical system 15
adjusted in accordance with the method for adjusting the optical
characteristic concerning this embodiment. Therefore, the image of the
pattern of the mask M can be formed at a high resolution on the wafer W.
In Step S301 to Step S305, the metal is vapor-deposited on the wafer W,
and the surface of the metal film is coated with the resist to perform
the respective steps of the exposure, the development, and the etching.
However, it goes without saying that a silicon oxide film may be formed
on the wafer W prior to these steps, and then the surface of the silicon
oxide film may be coated with the resist to perform the respective steps
of the exposure, the development, the etching, etc.

[0093]The present invention relates to the theme or the subject included
in Japanese Patent Application No. 2007-167857 filed on Jun. 26, 2007,
the entire disclosure of which is evidently incorporated herein by
reference.

[0094]The optical characteristic adjusting method of the present invention
is useful to measure the optical characteristic of the optical system
usable to produce the electronic device such as the semiconductor
element, the liquid crystal display element or the like in the
lithography step. The optical characteristic of the optical system can be
adjusted highly accurately by using the exposure apparatus provided with
the optical system adjusted in accordance with the optical characteristic
adjusting method of the present invention and the exposure method using
the exposure apparatus. The exposure apparatus, which is provided with
the optical system having the satisfactory optical characteristic, can be
produced in accordance with the exposure apparatus producing method for
producing the exposure apparatus.